| 摘要 |
PURPOSE:To widen the detection range of a light beam without increasing the number of photodetecting elements by providing the photodetecting elements relatively to an end surface of a rod-shaped light beam transmission body of an optional length which has a layer for the irregular reflection of light beams at the circumference. CONSTITUTION:A light beam 2 incident to a columnar glass body 1 is reflected irregularly by the irregular reflection layer 3, reflected by the internal surface of the glass body 1 and a reflecting mirror 5, and detected by the photodetecting element 4. The length L of this irregular reflection layer 3 is increased to detect all incident light beams without increasing the number of photodetectors. Plural glass bodies 1 are provided successively, clamped by a frame body, and fitted to a ground moving body 8 so that its lengthwise direction coincides with a route 9 drawn by the light beam 2 emitted from a light beam scanner 10, thereby guiding the ground moving body 8 along the path 9. |
